[#176] localstore: Draft storage engine shard structure and ops

Implement the primary structure and operation of the local object
storage shard.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/local_object_storage/shard/delete.go

@@ -0,0 +1,37 @@
+package shard
+
+import (
+	objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
+)
+
+// DeletePrm groups the parameters of Delete operation.
+type DeletePrm struct {
+	addr *objectSDK.Address
+}
+
+// DeleteRes groups resulting values of Delete operation.
+type DeleteRes struct{}
+
+// WithAddress is a Delete option to set the address of the object to delete.
+//
+// Option is required.
+func (p *DeletePrm) WithAddress(addr *objectSDK.Address) *DeletePrm {
+	if p != nil {
+		p.addr = addr
+	}
+
+	return p
+}
+
+// Delete marks object to delete from shard.
+//
+// Returns any error encountered that did not allow to completely
+// mark the object to delete.
+func (s *Shard) Delete(prm *DeletePrm) (*DeleteRes, error) {
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
+
+	// FIXME: implement me
+
+	return nil, nil
+}

pkg/local_object_storage/shard/exists.go

@@ -0,0 +1,43 @@
+package shard
+
+import (
+	"github.com/nspcc-dev/neofs-api-go/pkg/object"
+)
+
+// ExistsPrm groups the parameters of Exists operation.
+type ExistsPrm struct {
+	addr *object.Address
+}
+
+// ExistsRes groups resulting values of Exists operation.
+type ExistsRes struct {
+	ex bool
+}
+
+// WithAddress is an Exists option to set object checked for existence.
+func (p *ExistsPrm) WithAddress(addr *object.Address) *ExistsPrm {
+	if p != nil {
+		p.addr = addr
+	}
+
+	return p
+}
+
+// Exists returns the fact that the object is in the shard.
+func (p *ExistsRes) Exists() bool {
+	return p.ex
+}
+
+// Exists checks if object is presented in shard.
+//
+// Returns any error encountered that does not allow to
+// unambiguously determine the presence of an object.
+func (s *Shard) Exists(prm *ExistsPrm) (*ExistsRes, error) {
+	s.mtx.RLock()
+	defer s.mtx.RUnlock()
+
+	// FIXME: implement me
+	return &ExistsRes{
+		ex: false,
+	}, nil
+}

pkg/local_object_storage/shard/get.go

@@ -0,0 +1,79 @@
+package shard
+
+import (
+	"errors"
+
+	objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
+	"github.com/nspcc-dev/neofs-node/pkg/core/object"
+)
+
+// GetPrm groups the parameters of Get operation.
+type GetPrm struct {
+	ln int64 // negative value for full range
+
+	off uint64
+
+	addr *objectSDK.Address
+}
+
+// GetRes groups resulting values of Get operation.
+type GetRes struct {
+	obj *object.Object
+}
+
+// ErrObjectNotFound is returns on read operations requested on a missing object.
+var ErrObjectNotFound = errors.New("object not found")
+
+// WithAddress is a Get option to set the address of the requested object.
+//
+// Option is required.
+func (p *GetPrm) WithAddress(addr *objectSDK.Address) *GetPrm {
+	if p != nil {
+		p.addr = addr
+	}
+
+	return p
+}
+
+// WithFullRange is a Get option to receive full object payload.
+func (p *GetPrm) WithFullRange() *GetPrm {
+	if p != nil {
+		p.ln = -1
+	}
+
+	return p
+}
+
+// WithRange is a Get option to set range of requested payload data.
+//
+// Calling with negative length is equivalent
+// to getting the full payload range.
+func (p *GetPrm) WithRange(off uint64, ln int64) *GetPrm {
+	if p != nil {
+		p.off, p.ln = off, ln
+	}
+
+	return p
+}
+
+// Object returns the requested object part.
+//
+// Instance payload contains the requested range of the original object.
+func (r *GetRes) Object() *object.Object {
+	return r.obj
+}
+
+// Get reads part of an object from shard.
+//
+// Returns any error encountered that
+// did not allow to completely read the object part.
+//
+// Returns ErrObjectNotFound if requested object is missing in shard.
+func (s *Shard) Get(prm *GetPrm) (*GetRes, error) {
+	s.mtx.RLock()
+	defer s.mtx.RUnlock()
+
+	// FIXME: implement me
+
+	return nil, nil
+}

pkg/local_object_storage/shard/id.go

@@ -0,0 +1,21 @@
+package shard
+
+// ID represents Shard identifier.
+//
+// Each shard should have the unique ID within
+// a single instance of local storage.
+type ID []byte
+
+// NewIDFromBytes constructs ID from byte slice.
+func NewIDFromBytes(v []byte) *ID {
+	return (*ID)(&v)
+}
+
+func (id ID) String() string {
+	return string(id)
+}
+
+// ID returns Shard identifier.
+func (s *Shard) ID() *ID {
+	return s.id
+}

pkg/local_object_storage/shard/put.go

@@ -0,0 +1,35 @@
+package shard
+
+import (
+	"github.com/nspcc-dev/neofs-node/pkg/core/object"
+)
+
+// PutPrm groups the parameters of Put operation.
+type PutPrm struct {
+	obj *object.Object
+}
+
+// PutRes groups resulting values of Put operation.
+type PutRes struct{}
+
+// WithObject is a Put option to set object to save.
+func (p *PutPrm) WithObject(obj *object.Object) *PutPrm {
+	if p != nil {
+		p.obj = obj
+	}
+
+	return p
+}
+
+// Put saves the object in shard.
+//
+// Returns any error encountered that
+// did not allow to completely save the object.
+func (s *Shard) Put(prm *PutPrm) (*PutRes, error) {
+	s.mtx.Lock()
+	defer s.mtx.Unlock()
+
+	// FIXME: implement me
+
+	return nil, nil
+}

pkg/local_object_storage/shard/select.go

@@ -0,0 +1,42 @@
+package shard
+
+import (
+	objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
+)
+
+// SelectPrm groups the parameters of Select operation.
+type SelectPrm struct {
+	filters objectSDK.SearchFilters
+}
+
+// SelectRes groups resulting values of Select operation.
+type SelectRes struct {
+	addrList []*objectSDK.Address
+}
+
+// WithFilters is a Select option to set the object filters.
+func (p *SelectPrm) WithFilters(fs objectSDK.SearchFilters) *SelectPrm {
+	if p != nil {
+		p.filters = fs
+	}
+
+	return p
+}
+
+// AddressList returns list of addresses of the selected objects.
+func (r *SelectRes) AddressList() []*objectSDK.Address {
+	return r.addrList
+}
+
+// Select selects the objects from shard that match select parameters.
+//
+// Returns any error encountered that
+// did not allow to completely select the objects.
+func (s *Shard) Select(prm *SelectPrm) (*SelectRes, error) {
+	s.mtx.RLock()
+	defer s.mtx.RUnlock()
+
+	// FIXME: implement me
+
+	return nil, nil
+}

pkg/local_object_storage/shard/shard.go

@@ -0,0 +1,46 @@
+package shard
+
+import (
+	"sync"
+)
+
+// Shard represents single shard of NeoFS Local Storage Engine.
+type Shard struct {
+	*cfg
+
+	mtx *sync.RWMutex
+
+	weight WeightValues
+}
+
+// Option represents Shard's constructor option.
+type Option func(*cfg)
+
+type cfg struct {
+	id *ID
+}
+
+func defaultCfg() *cfg {
+	return new(cfg)
+}
+
+// New creates, initializes and returns new Shard instance.
+func New(opts ...Option) *Shard {
+	c := defaultCfg()
+
+	for i := range opts {
+		opts[i](c)
+	}
+
+	return &Shard{
+		cfg: c,
+		mtx: new(sync.RWMutex),
+	}
+}
+
+// WithID returns option to set shard identifier.
+func WithID(id *ID) Option {
+	return func(c *cfg) {
+		c.id = id
+	}
+}

pkg/local_object_storage/shard/weight.go

@@ -0,0 +1,12 @@
+package shard
+
+// WeightValues groups values of Shard weight parameters.
+type WeightValues struct {
+	// Amount of free disk space. Measured in kilobytes.
+	FreeSpace uint64
+}
+
+// WeightValues returns current weight values of the Shard.
+func (s *Shard) WeightValues() WeightValues {
+	return s.weight
+}